CTI BioPharma Corp. (CTI BioPharma) (Nasdaq: CTIC) announced top-line results from PERSIST-2, a randomized, controlled Phase 3 clinical trial comparing pacritinib, an investigational oral multikinase inhibitor, with physician-specified best available therapy (BAT), including ruxolitinib, for the treatment of patients with myelofibrosis whose platelet counts are less than 100,000 per microliter -- a patient population with high-risk advanced disease. Three hundred eleven (311) patients were enrolled in the study, which formed the basis for the safety analysis. Two hundred twenty-one (221) patients who had a chance to reach Week 24 (the primary analysis time point) at the time the clinical hold was imposed and constituted the intent-to-treat (ITT) analysis population utilized for the evaluation of efficacy. Preliminary results demonstrated that the PERSIST-2 trial met one of the co-primary endpoints showing a statistically significant response rate in spleen volume reduction (SVR) in patients with myelofibrosis treated with pacritinib compared to BAT, including the approved JAK2 inhibitor ruxolitinib (p<0.01). Although the PERSIST-2 trial did not meet the other co-primary endpoint of greater than 50 percent reduction in Total Symptom Score (TSS), the preliminary analysis approached marginal significance compared to BAT (p=0.0791).

"Unlike patients with myelofibrosis who have normal baseline platelet counts where median survival is reported at 88 months, we recently reported from our institution's experience that patients with severe thrombocytopenia (low platelets) had a median survival of about 14 months," said Srdan (Serge) Verstovsek, M.D., Ph.D., Director, Clinical Research Center for MPNs at the University of Texas MD Anderson Cancer Center and principal investigator for the PERSIST-2 Phase 3 clinical trial of pacritinib. "These patients represent up to 30 percent of all myelofibrosis patients and an unmet medical need. Data from the PERSIST-2 prospective randomized, controlled trial is encouraging because we need an effective therapy to treat the most challenging patients with low platelet counts we see in our practice."

The co-primary endpoints of the trial were the proportion of patients achieving a 35 percent or greater reduction in spleen volume from baseline to Week 24 as measured by magnetic resonance imaging (MRI) or computerized tomography (CT) and the proportion of patients achieving a Total Symptom Score (TSS) reduction of 50 percent or greater using MPN-SAF TSS 2.0 diary from baseline to Week 24.

The most common treatment emergent adverse events for pacritinib were generally manageable diarrhea, nausea and vomiting. The incidence of cardiac and bleeding adverse events (all grades and grade 3-4 including deaths) were similar across the arms. Overall mortality rates were comparable between arms. Additional data from ongoing analyses along with top-line results from PERSIST-2 will be submitted for presentation at an upcoming scientific meeting.

Myelofibrosis is associated with significantly reduced quality of life and shortened survival. Spleen enlargement (splenomegaly) is a common and debilitating symptom of myelofibrosis. As the disease progresses, the body slows production of important blood cells and within one year of diagnosis the incidence of disease-related thrombocytopenia (very low blood platelet counts), severe anemia and red blood cell transfusion requirements increase significantly.

"Having analyzed data from two Phase 3 trials with the only JAK inhibitor to be studied in severely thrombocytopenic patients, including patients on JAK2 therapy or those who failed prior JAK2, we are encouraged by pacritinib's clinical profile in this difficult-to-treat group of patients with myelofibrosis," said James A. Bianco, M.D., President and Chief Executive Officer, CTI BioPharma. "We are grateful for the support and commitment of the investigators, our steering committee and, most importantly, all the patients who participated in PERSIST-2."